Typical operating window
February–AprilWinter storms build the base before operations concentrate on late-winter depth and longer spring light.Verified planning context
Snow, weather and avalanche context
Historical patterns help you compare trips. They do not predict your week or replace the operator's daily decisions.
Strongest comparable snow evidence
237 cm median · 200–273 cm interquartile rangeNOAA GHCN station USC00507783, PuntillaTier B · observed reference · low confidenceSnow character
transitionalThe range combines maritime moisture with colder inland influence, creating large storm-to-storm changes.Public avalanche information
No verified staffed public forecast for the full tenureNearby public products may not cover the Tordrillos. The operator assessment is the operational source.Weather and flight context
Gulf moisture, interior cold, volcanic terrain, and limited observations interact.
- Remote weather gaps
- All-alpine flat light
- Wind and volcanic terrain
Meteorological reference area
Tordrillo Mountains
- Includes
- Tordrillo Mountains and named nearby reference stations.
- Excludes
- Chugach and generic Alaska evidence.
- Elevation
- No verified operator-terrain elevation band is public. Each evidence value retains its site elevation.
Evidence pack
Measurements, claims and gaps stay separate.
Tier BRemote reference-station snowfall237 cm median · 200–273 cm interquartile range
- Site
- NOAA GHCN station USC00507783, Puntilla · 62.0911, -152.7350 · 566 m · 78 km from the catalogue reference
- Period
- July–June snow years, 1991/92–2019/20
- Completeness
- 15 of 29 snow years had at least 330 valid daily snowfall values.
- Method
- Quality-flagged daily SNOW values summed by snow year; incomplete years excluded.
- Limitation
- The distant, low station does not represent high Tordrillo terrain. It is context only.
- Global Historical Climatology Network DailyNOAA National Centers for Environmental Information · accessed 2026-08-25
Tier CModelled snowfall water equivalent1,441 mm SWE median · 1,335–1,514 mm interquartile range
- Site
- Tordrillo catalogue location ERA5-Land grid cell · 61.4000, -152.4000 · 1.2 km from Tordrillo catalogue location reference point
- Period
- Calendar years 1991–2020
- Completeness
- 360 monthly means; all 30 calendar years contain 12 values.
- Method
- ERA5-Land monthly mean daily snowfall accumulation was multiplied by calendar days and 1,000, then summed by calendar year.
- Limitation
- This reference area supports evidence discovery and comparison. It is not an operating-area or tenure boundary. This unadjusted 0.1° reanalysis grid cell is not an observation, snow depth, or terrain-wide total. Grid elevation and wind redistribution can cause substantial local bias.
- ERA5-Land monthly averaged data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-26
Monthly evidence
Each cell keeps its measurement type and unit. Reanalysis water equivalent is not snow depth. Text-only cells preserve a representative data gap.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 34.3 cm snowfall | 25.2 cm snowfall | 19.6 cm snowfall | 7.6 cm snowfall | 0 cm snowfall | 0 cm snowfall | 0 cm snowfall | 0 cm snowfall | 0 cm snowfall | 21.8 cm snowfall | 42.9 cm snowfall | 59.6 cm snowfall |
Commercial operator assessment
Operator assessment process not independently verifiedThe operator must assess current snow, avalanche terrain, weather, aircraft limits, and rescue options. No private operational plan is inferred.
Sources and evidence notes
- U.S. Climate Normals 1991–2020NOAA National Centers for Environmental Information · accessed 2026-08-25
- ERA5-Land hourly data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-25
- Published operator and trip inventoryHeliski International editorial team · accessed 2026-08-25
- Global Historical Climatology Network DailyNOAA National Centers for Environmental Information · accessed 2026-08-25
- ERA5-Land monthly averaged data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-26
- Alaska avalanche forecast centersAvalanche.org · accessed 2026-08-25